A renal scan is a test that is often used to test kidney function. During this test, a small amount of radioactive material is injected into a vein. A few minutes later, a machine is used to scan and take pictures of the kidneys. This test can often determine such things as blood flow to the kidneys or if there is any urine backing up into the kidney once it has left the kidney, a condition known as urinary reflux. A renal scan is a simple outpatient procedure and requires no recovery time for the patient.
A renal scan will often be ordered by a physician if the patient is suspected of having a kidney disease or impaired kidney function. The goal of this test is to measure the size of the kidneys as well as to tell if there is any functional impairment, such as urinary reflux or a problem with proper blood flow to the kidneys.
Just before the renal scan is performed, a small amount of radioactive material, referred to as a radioisotope, is injected into a vein, typically in the arm. Adverse reactions to this substance are very rare, so it is considered to be a safe form of testing. Depending upon the medications normally taken by the patient, the doctor may recommend not taking any medications that may negatively affect the test until after the renal scan has been completed. It is generally recommended that the patient drink plenty of fluids prior to the test.
A few minutes after the injection, the renal scan itself will begin. This consists of several images, or pictures, being taken of the kidneys. These pictures are taken several minutes apart. The entire procedure generally takes between 30 minutes to an hour.
Once the renal scan has been completed, a computer will process all of the information gathered from the images. This information will allow the computer to measure the size of the kidneys as well as determine the amount of function. The doctor will then use this information in making a diagnosis.
After the renal scan, it is generally advisable to drink plenty of fluids in order to flush all of the radioactive material out from the body. In some cases, the patient may find out the results of the renal scan on the same day as the procedure. It is more common, however, to get the results at a follow-up visit with the ordering physician.